Method for manufacturing thin film transistor using oxide semiconductor and display apparatus

Abstract

A thin film transistor is manufactured by forming a gate electrode on a substrate, forming a first insulating film on the gate electrode, forming an oxide semiconductor layer on the first insulating film with an amorphous oxide, patterning the first insulating film, patterning the oxide semiconductor layer, forming a second insulating film on the oxide semiconductor layer in an oxidative-gas-containing atmosphere, patterning the second insulating film to expose a pair of contact regions, forming an electrode layer on the pair of contact regions, and patterning the electrode layer to for a source electrode and a drain electrode.

1. A method of manufacturing a thin film transistor having on a substrate, at least a gate electrode, a first insulating film, an oxide semiconductor layer, a second insulating film, a source electrode and a drain electrode, comprising the steps of:
 forming a gate electrode on a substrate; 
 forming a first insulating film on the gate electrode; 
 forming an oxide semiconductor layer on the first insulating film with an amorphous oxide containing at least In and Zn; 
 patterning the first insulating film; 
 patterning the oxide semiconductor layer; 
 forming a second insulating film on the oxide semiconductor layer in an oxidative-gas-containing atmosphere; 
 patterning the second insulating film to expose a pair of contact regions in the oxide semiconductor layer and lower the electric resistance of the contact regions by generating oxygen defects in the contact regions; 
 forming an electrode layer on the pair of contact regions; and 
 patterning the electrode layer to form a source electrode and a drain electrode. 
 
     
     
       2. The method according to  claim 1 , wherein a mixture gas of O 2 /Ar is used for the oxidative-gas-containing atmosphere and the mixture ratio is not less than 10 vol %. 
     
     
       3. The method according to  claim 1 , wherein the amorphous oxide contains In, Zn and Ga. 
     
     
       4. The method according to  claim 1 , wherein the second insulating film is an amorphous oxide insulator containing oxygen atoms such that the level of O 2   +  observed as desorbed gas by means of temperature programmed desorption mass spectrometry is not less than 3.8×10 19 /cm 3 . 
     
     
       5. A thin film transistor having on a substrate, at least a gate electrode, an oxide semiconductor layer, an insulating film, a source electrode and a drain electrode, and having been manufactured by the manufacturing method according to  claim 1 . 
     
     
       6. A display apparatus comprising a display device, an electrode for supplying an electric signal to the display device and the thin film transistor according to  claim 5  for driving the display device, wherein the source or drain electrode of the thin film transistor is connected to an electrode of the display device. 
     
     
       7. The apparatus according to  claim 6 , wherein the device is an electroluminescent device. 
     
     
       8. The apparatus according to  claim 6 , wherein the device is a liquid crystal cell. 
     
     
       9. The apparatus according to  claim 6 , wherein a plurality of display devices and a plurality of thin film transistors are arranged two-dimensionally on a substrate. 
     
     
       10. A method of manufacturing a thin film transistor having on a substrate, at least a gate electrode, an oxide semiconductor layer, an insulating film, a source electrode and a drain electrode, comprising the steps of:
 forming an oxide semiconductor layer on a substrate with an amorphous oxide containing at least In and Zn; 
 patterning the oxide semiconductor layer; 
 forming an insulating film on the oxide semiconductor layer in an oxidative-gas-containing atmosphere; 
 patterning the insulating film to expose a pair of contact regions in the oxide semiconductor layer and lower the electric resistance of the pair of contact regions by generating oxygen defects in the contact regions; 
 forming an electrode layer on the pair of contact regions and on the insulating film; and 
 patterning the electrode layer to form a source electrode, a drain electrode and a gate electrode.